Do You Need a Filament Dryer? Signs of Wet Filament and How to Dry It

Do you need a filament dryer? For PETG, TPU, ASA, ABS, nylon and polycarbonate, a dryer is basically required, according to 3DPrintSOS, a YouTube channel that tested nine filament dryers. For plain PLA, you “might not necessarily need” one, the channel said, though it still helps.

Moisture builds up fast. In a typical room at about 55% relative humidity, freshly dried filament usually absorbs enough water to affect print quality within 2 to 12 hours, depending on the material, according to Bambu Lab Wiki, “Filament Drying Recommendations”. Below are the signs of wet filament, Bambu Lab’s drying temperatures, a free method and what dryers cost.

Signs Your Filament Is Wet

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Most filaments are hygroscopic, meaning they “soak up water like a sponge,” according to 3D Print Dood, “What is a Filament Dryer? And Do You Really Need It?”. In the hot nozzle, that moisture turns to vapor and makes the plastic expand and extrude unevenly. Bambu Lab lists the results:

• Stringing and oozing
• Bubbles, holes and popping or crackling sounds
• Rough surfaces
• Lower strength

3DPrintSOS said wet nylon carbon fiber can come out pale and so brittle you can break prints by hand, because layer adhesion suffers. Drying the same spool and printing on the same settings usually gives a much better result, the channel said.

Which Filaments Need Drying Most?

3D Print Dood says PLA isn’t as sensitive, so you can often get away without a dryer, but for PETG, TPU or nylon a dryer can be “a total game changer” (3D Print Dood, “What is a Filament Dryer? And Do You Really Need It?”). For the difference between the two common beginner filaments, see PLA vs PETG.

Drying Temperatures and Times

These are Bambu Lab’s recommendations for its own filaments (Bambu Lab Wiki, “Filament Drying Recommendations”). Other brands may list different settings on the spool, so check the label first.

Heated-bed temperatures are higher than oven temperatures because the bed heats the spool from one side under a cover. Bambu Lab also warns against microwaves and kitchen ovens, which heat unevenly and can damage a spool.

Free Option: Dry Filament on Your Printer

3DPrintSOS calls this the number one thing you can do without buying anything: set the spool on the heated bed, cover it with a cardboard box such as the filament’s own box, and set the bed temperature. Some enclosed printers have a built-in drying setting. The catch is that you can’t print while it dries (3DPrintSOS, “I TESTED 9 FILAMENT DRYERS SO YOU CAN HAVE BETTER PRINTS!”).

Bambu Lab’s steps for its enclosed printers:

• Unload the filament from the toolhead so it doesn’t soften inside the extruder.
• Place the spool on the bed and cover it with the filament box or a lid printed in a heat-resistant material such as PC.
• Set the bed temperature and time from the table above.
• Flip the spool halfway through, wearing gloves.
• When finished, let it cool, then seal it with desiccant right away.

Bambu Lab says its open-frame P1P, A1 and A1 mini can’t be used to dry filament this way, and that some third-party spools may deform from the heat. The P1S has no built-in drying mode, so you set the bed temperature and time it yourself.

Filament Dryers 3DPrintSOS Tested

Prices are the approximate figures 3DPrintSOS gave in the video and change often (3DPrintSOS, “I TESTED 9 FILAMENT DRYERS SO YOU CAN HAVE BETTER PRINTS!”). The channel said the Space Pi X4’s glass touchscreen was the best of the group and that it would recommend the X4 “more than any single one.” For a single spool on a budget, it called the $70 Space Pi worth the price.

Built-In Drying: Bambu Lab AMS 2 Pro

The Bambu Lab P2S Combo comes with the AMS 2 Pro, which can dry filaments that need 65°C or less, according to Bambu Lab. It can power one AMS 2 Pro for drying directly from the printer. If you print while drying, the AMS automatically drops to 45°C for PLA or 55°C for PETG to avoid clogs. The P2S Combo listed at $779.00 on Amazon (check price).

How to Keep Filament Dry After Drying

• Store it in a sealed bag or box with desiccant. Bambu Lab says most filaments only stay dry below about 20% relative humidity, and even then for roughly 2 to 7 days.
• Use a hygrometer inside the box to see the real humidity.
• 3DPrintSOS uses color-changing orange silica gel that turns dark when wet and can be dried again.
• Dry PC once and keep it sealed: Bambu Lab says repeated heating and cooling can make PC filament brittle.

Video: 3DPrintSOS, “I TESTED 9 FILAMENT DRYERS SO YOU CAN HAVE BETTER PRINTS!”. Embedded with credit; the findings are the creator’s own.

Frequently Asked Questions

Does PLA need to be dried?

Not always. Bambu Lab recommends it before use, at 50°C for 8 hours in an oven, but PLA is less sensitive than PETG or TPU.

Can I dry filament without a dryer?

Yes, on the heated bed of an enclosed printer, with a box over the spool. You can’t print at the same time, and Bambu Lab says open-frame A1 printers can’t do it.

How long does filament stay dry?

In a normal room at about 55% humidity, only 2 to 12 hours before quality drops, Bambu Lab says. Sealed with desiccant, much longer.

Can I use my kitchen oven?

Bambu Lab advises against it, because kitchen ovens heat unevenly and can damage the spool.

What filaments need drying most?

TPU, PC, nylon and PVA. Bambu Lab lists drying as required for each.

Sources

• Bambu Lab Wiki, “Filament Drying Recommendations”
• 3DPrintSOS, “I TESTED 9 FILAMENT DRYERS SO YOU CAN HAVE BETTER PRINTS!”
• 3D Print Dood, “What is a Filament Dryer? And Do You Really Need It?”
• Amazon product listing for the Bambu Lab P2S Combo, October 17, 2026

Related: PLA vs PETG for Beginners | 3D Printed Filament Storage | Bambu Lab A1 Review | Best 3D Printer for Beginners